1. Field of the Invention
The present invention relates to a camera with a visual line position detection device that determines a photographer's visual line position and executes auto focus adjustment, auto exposure, and/or switching of shooting modes, based on the detected visual line position.
2. Description of Related Art
In recent years, with the development of electronic circuits and the photoelectric conversion device, automation and multi-functionality of cameras has progressed. Today, functions such as auto exposure detection and auto focus detection are provided in most cameras. Due to such automation and multi-functionality in cameras, photographers without much experience or advanced shooting skills are beginning to be able to take pictures with increased success.
On the other hand, because of the automation and multi-functionality of cameras, some shooting functions are sometimes restricted. Such restrictions result from the fact that adjustments of auto exposure and auto focus are structured to function for only part of the finder field.
In other words, in the case of auto exposure, appropriate exposure is established for most of the subjects by using a multi-photometry technique, etc., wherein the shooting field is divided into several areas, selection of the area to be established for appropriate exposure being accomplished based upon a measured difference between the absolute value of the photometric value of each area and the photometric value of the other areas.
On the other hand, in the case of auto focus adjustment, most cameras are structured in such a manner that auto focus adjustment is possible only in the middle of the finder field. As a result, if a subject for which focus detection is desired to be performed is not in the middle of the finder field, a shooting technique is necessary wherein focus detection is executed on the desired subject first, and then, maintaining the conditions intact, the framing is changed to take the picture.
In recent years, in order to avoid the maneuver described above, a camera has been invented wherein several points for auto focusing are provided in the finder field so that one of these points may be selected for auto focus adjustment.
Two known selection methods of a point in which auto focus adjustment are: (1) a method of using a microprocessor to automatically select a point by measuring the distance to each auto focus adjustment point and to use the distance obtained between each point and the subject, and (2) a method in which a point is selected manually by adjusting a command dial while watching the field.
Also, a method is known in which the point described above is selected by detecting and using the visual line position of the photographer. In this case, the photographer, while viewing through the finder, aligns his vision with a visual line position or point where he desires to execute auto focus adjustment, and a visual line position determinating device determines the visual line position and selects the point closest to the visual line position detected.
The selection method based on the visual line position described above is not limited to auto focus detection, but can be applied in a similar manner to change the settings of the camera, such as exposure mode and shutter speed, by establishing various areas on the screen field and having the photographer align his vision with an appropriate area.
A visual line position detection device is known, for example, wherein a reflected image of an eyeball, obtained when the photographer's eye surface is illuminated, is detected by a CCD sensor, the visual line position being determined by numerically converting the position on the sensor to a position in the field.
In determining the photographer's visual line position in the manner described above, sometimes the position in the finder field where the photographer is actually aligning his vision and the position of the visual line in the field determined by the visual line position detection device differ. In such a situation, it becomes necessary to correct the positional error between the visual line position point of the photographer and the visual line position determined by the visual line position detection device.
As a correction method in a visual line position detection device, a method is known wherein the photographer's line of sight is made to be aligned with a specified point on the finder screen. The visual line position detection device determines the photographer's visual line while maintaining the photographer's visual line position and corrects conversion coefficients from the sensor output of the visual line position detection device to the visual line position based on the difference in positions of the point detected in the finder field and the specified point to which the photographer aligns his vision.
On the other hand, there are cases in which the subject image is not clearly observed on the screen, depending on the difference in the diopter of photographers and on whether or not correction is made for eyeglasses or contact lenses. In such cases, the diopter needs to be adjusted in the finder, etc., of the camera.
As a method of diopter adjustment, several conventional methods are known, such as a method in which the eyepiece is changed to a lens matching the diopter and a method in which the diopter is adjusted by providing a movable diopter adjustment lens within the finder and by moving the diopter adjustment lens forward and backward in the direction of the optical axis.
However, with the conventional methods described above, the diopter adjustment lens is positioned between the photographer's eye and the sensor of the visual line position detection device and the screen field. Because of this, problems occur. For example, if a photographer with eyeglasses removes the glasses and executes diopter adjustment after correction of the visual line detection system is completed, the position of the diopter adjustment lens changes and the visual line detection system erroneously detects a point different from the photographer's actual line of vision.